The invention relates to a vascular catheter for cannulating arterial or venous vessels, for example, in the femoral region, or the vena cava and the right auricle of the heart, comprising of a flexible tube having blood passage orifices in the nature of holes at its anterior end (insertion end) to be inserted in the vessel or auricle as the case may be, the other end of the tube being directly or indirectly connectable to some other conduit or instrument.
Such catheters are employed in particular as venous return catheters in connection with heart-lung machines, which in cardiac surgery temporarily assume the function of the patient's heart and lungs. The purpose served by the catheter is to draw the blood returning to the patient's heart form the right auricle, or the inferior vena cava opening thereinto, and supply it to the heart-lung machine, or the pump to circulate the blood.
U.S. Pat. No. 4,129,129 discloses a return catheter of the kind mentioned above, which at its insertion tip comprises a first basket with elongated blood inlet orifices and, at a distance from this insertion tip, a second basket with additional elongated blood inlet orifices. In use, the first basket of this catheter is passed through the auricle of the heart into the inferior vena cava, bringing the second basket into the right auricle. This counteracts a reduction of venous drainage brought about by distortion of the arterial walls and of the vena cava or by change of position of the catheter.
A single catheter cannulation is also described in the reference "Single Catheter Gravity Drainage of the Right Atrium or Right Ventricle During Total Cardiac Bypass," by G. C. Blanco, et al., Dis. Chest, 35, pg. 554-560, May 1959. On page 555 of this reference, the catheter is shown to have multiple perforations in the distal portion of its body, and is positioned so that these perforations extend from the right atrium down to the inferior vena cava. The perforations are in such a position that they collect blood from both the right atrium and the inferior vena cava utilizing a single catheter.
With these and most other known catheters having blood passage orifices distributed along the length of the catheter, however, the problem raises that from the commencement of insertion of the catheter in the vessel or the auricle, blood enters through the foremost orifices at the insertion tip. Therefore, the insertion of the catheter must take place slowly and with care. As the orifices in the catheter are placed in the auricle or vessel the blood fills the tube, and a considerable quantity of blood may escape from the vessel, or the auricle, into the patient's body.